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Heating trouble

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Hi all. I have recently had a new combi boiler fitted Nd the lads have done cracking job however, it appears I may have a leak somewhere. I used to have to top the old boiler up quite regularly becau… Read More
GrassSnakeUK Avatar
2w, 2d agoPosted 2 weeks, 2 days ago
Hi all.
I have recently had a new combi boiler fitted Nd the lads have done cracking job however, it appears I may have a leak somewhere. I used to have to top the old boiler up quite regularly because if a leak on the manifold (hence the change) but since Saturday and the boiler swap I have had to top up the boiler already. I have a call out to the engineer but to be fair I'm expecting, " the boiler we fitted doesn't leak" and I feel it would be a fair comment...

I have checked all of my rads valves for anything obvious and they are dry and there are no signs of any leaks in any of ceilings. Ground floor is concrete floors so all the pipes are in loft or between ground floor and 1st floor. Any thoughts would be appreciated.

Thanks in advance.
GrassSnakeUK Avatar
2w, 2d agoPosted 2 weeks, 2 days ago
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Responses/page:
#1
If it was fitted very recent it will just be the air in the system left in. Thats if you mean by topping up with the pressure guage.
#2
Older boilers can have an internal leak that just get evaporated off with no signs of water. It's what happend to ours but was fixed. Cracked heat exchanger i think. Shouldn't have that with a new one
#3
Only fitted Saturday, I noticed the rads didn't get bled (so the Mrs tells me, I was out) and when I was topping pressure up today the boiler was calling for heat and the huge was fluctuating when it was firing.

Edited By: GrassSnakeUK on Apr 10, 2017 19:23
#4
as the first post says proberbly air, give all the radiators a good bleed and keep checking and bleeding and topping up for the next few days if you are using the system. should settle down
#5
Numpty fitters who didn't even bother to bleed rads on commissioning. Get the lazy twits back to do the job you paid them for, at the same time make sure they've filled in your benchmark at the back of the manual, and notified the boiler to Gas Safe.
#6
They did all the gas tests and filled in warranty paperwork. I assumed they would have bled system as well... I can do it myself. Any thoughts on which if any radiators to do 1st or last?
#7
GrassSnakeUK
They did all the gas tests and filled in warranty paperwork. I assumed they would have bled system as well... I can do it myself. Any thoughts on which if any radiators to do 1st or last?

bleed downstairs then upstairs,
only top pressure up when cold as you will only get a true reading then.
should be around 1.1 - 1.5 while cold, then expand to 2.0-2.4(ish) when hot.

(gas + heating engineer 10 years)
#8
Can I bleed them hot or cold?
#9
new boilers should be installed with a power flush. there may be a slow leak somewhere in your system. i had a slow leak in my central heating system which was never got to the bottom of so the boiler had to be repressurised every 6 months or so.

a lot of my pipes were under floor boards so it was not easy to investigate any slow leaks.

how to bleed radiators here

http://ketchup.homeserve.com/handy-hints/boilers/radiators/radiator-maintenance/how-to-bleed-a-radiator/
#10
GrassSnakeUK
Can I bleed them hot or cold?


u will need have the heating on to give it pressure will make it easier for u also before blend them see if the heaters are just heating at the bottom or 1 side only there will be quite a a lot of air in them so pressure it up to say 1.5 bars if that's the case then bleed them if u got 2 people they can pressure it whilst u bleed it if u don't then the boiler may go off if pressure goes to low when air comes out u will need to do it a few times if they haven't done it at all.
#11
mutley1
new boilers should be installed with a power flush. there may be a slow leak somewhere in your system. i had a slow leak in my central heating system which was never got to the bottom of so the boiler had to be repressurised every 6 months or so.
a lot of my pipes were under floor boards so it was not easy to investigate any slow leaks.
how to bleed radiators herehttp://ketchup.homeserve.com/handy-hints/boilers/radiators/radiator-maintenance/how-to-bleed-a-radiator/
No need for a power flush in most cases. Dodgy plumbers just trying to get an extra £300!
#12
chocci
mutley1
new boilers should be installed with a power flush. there may be a slow leak somewhere in your system. i had a slow leak in my central heating system which was never got to the bottom of so the boiler had to be repressurised every 6 months or so.
a lot of my pipes were under floor boards so it was not easy to investigate any slow leaks.
how to bleed radiators herehttp://ketchup.homeserve.com/handy-hints/boilers/radiators/radiator-maintenance/how-to-bleed-a-radiator/
No need for a power flush in most cases. Dodgy plumbers just trying to get an extra £300!

So what happens to all the crap in a system when it get's carried through the small waterways of a heat exchanger, diverter valve, and plate heat exchanger.

Long warranties are unsustainable for most boiler manufacturers, dirty system water is the easiest get out for all of them. Also I find a power flush saves time when completing a system flush to BS7593.
#13
chocci
mutley1
new boilers should be installed with a power flush. there may be a slow leak somewhere in your system. i had a slow leak in my central heating system which was never got to the bottom of so the boiler had to be repressurised every 6 months or so.
a lot of my pipes were under floor boards so it was not easy to investigate any slow leaks.
how to bleed radiators herehttp://ketchup.homeserve.com/handy-hints/boilers/radiators/radiator-maintenance/how-to-bleed-a-radiator/
No need for a power flush in most cases. Dodgy plumbers just trying to get an extra £300!

as the poster said above, may not be needed but a boiler should last about 10 years so when a boiler gets replaced, it would be appropriate time to give the complete system a power flush so that the new boiler is not compromised. i would guess that a new boiler would work more efficiently with a clean system. as the engineers are already there installing the new boiler, there will be economy of scale to get them to do the power flush at the same time as they are already on site.

i find my plumbers are actually quite resistant to do the powerflush as they don't make the most money from that as they do from the install itself so i always have to make a specific request to get this done and i can see their faces don't exactly light up with dollar signs even though they charge me for the power flush.
#14
Because of the trouble with the previous system the boiler had been drained more times than me! Therefore the system water was quite clean.
The lads have included and installed a "magna clean" and he is coming back next week to clean it.
How would the power flush help with a leak or drop in pressure though?

Thanks.
Grass.
#15
themorgatron
chocci
mutley1
new boilers should be installed with a power flush. there may be a slow leak somewhere in your system. i had a slow leak in my central heating system which was never got to the bottom of so the boiler had to be repressurised every 6 months or so.
a lot of my pipes were under floor boards so it was not easy to investigate any slow leaks.
how to bleed radiators herehttp://ketchup.homeserve.com/handy-hints/boilers/radiators/radiator-maintenance/how-to-bleed-a-radiator/
No need for a power flush in most cases. Dodgy plumbers just trying to get an extra £300!
So what happens to all the crap in a system when it get's carried through the small waterways of a heat exchanger, diverter valve, and plate heat exchanger.
Long warranties are unsustainable for most boiler manufacturers, dirty system water is the easiest get out for all of them. Also I find a power flush saves time when completing a system flush to BS7593.
As I said, its generally not needed. The system should have been drained anyway when fitting the new boiler. Guess it depends how much sludge in the system. I just drained mine the other day after not draining for 7 years and the water was pretty much clear.
#16
on this topic, wheres the best/cheapest place to get a system boiler(to run 18 rads) and a unvented indirect hot water cylinder(between 200L and 300L) please. been told by my plumber I'd be best going for a 42kw boiler.

been checking ebay and gumtree but no joy. thought maybe some of you guys in the trade may know a reputable 2nd hand seller(s).

Pm me if you know of any. thanks <3
#17
Unfortunately the more you drain and refill a system the worse the corrosion becomes due to oxidisation. It is not surprising that after seven years of being left alone your water was clear.

Second hand is not usually a good way to go neither for appliances.

As for filling up, please ignore previous advice of filling when heating is on as you will not get an accurate final reading of the pressure.
#18
Also an easy way to rule out a leak on the boiler or system is to isolate the system at the boiler and check to see if the pressure drops over a few days. Usually a leak can be so small that you can't even notice a drip but lose pressure. Plastic flow and returns contribute to this problem. Leak sealer can be very useful but some manufacturers don't approve its use because it can block heat exchangers.
#19
chocci
mutley1
new boilers should be installed with a power flush. there may be a slow leak somewhere in your system. i had a slow leak in my central heating system which was never got to the bottom of so the boiler had to be repressurised every 6 months or so.
a lot of my pipes were under floor boards so it was not easy to investigate any slow leaks.
how to bleed radiators herehttp://ketchup.homeserve.com/handy-hints/boilers/radiators/radiator-maintenance/how-to-bleed-a-radiator/
No need for a power flush in most cases. Dodgy plumbers just trying to get an extra £300!


No, it's dodgy manufacturers using the lack of clean system water to get out of warranty calls and tight customers not wanting to spend £350+ on a useful service if it is needed.
#20
Thanks so much for everyones replies

Trust me spending 350 quid on something that was needed wouldn't worry me but when a highly recommended heating engineer tells me that it doesn't need flushing, I don't get it flushed. (Seeing as he didn't bleed the rads....). I'm sure the magna clean will help as well.
However, my point/query was regarding the drop in pressure....
So should I re-fill the system hot or cold?
Mixed opinions it would seem.
#21
"Tight customers" wasn't directed at yourself.

There is a test using a thin test tube with circles that will say for sure whether a flush is needed but guessing he did that.

As for pressurising, if you fill up cold and top up to around 1 bar you get a stable level. If the water is hot it has expanded hence heightened the pressure but you will not know by how much so you could leave it well above where it should be and worst case if, when the heating is on it goes above 3 bar then the prv kicks in and may not reseat properly and you're spending on a replacement. Depending on the boiler this can be a pig of a job too.

Far easier to just top up when cold
#22
Powerflush is nothing to do with the pressure drop BTW
#23
So woke up this morning. Boiler empty.
Puddle under towel rad 1st floor bathroom. Tap tap tap tap in kitchen ceiling below.
#24
Matt1082villa. I'm sure no offence was implied or intended and I certainly didn't take any!
#25
Awesome, check the bleed valve on towel rad. May have been left open. Failing that it's not usually a big job to fix or nip the fitting up
#26
Will probably fix the dropping pressure too
#27
2 x leaking service valves bottom of towel rad. 1 fixed plumber coming back to do of her one as he only had one with him.
#28
GrassSnakeUK
2 x leaking service valves bottom of towel rad. 1 fixed plumber coming back to do of her one as he only had one with him.

Service valves or radiator valves? If they're the slotted isolation valves you turn off with a screwdriver expect them to leak again if he's replacing like for like.
#29
themorgatron
GrassSnakeUK
2 x leaking service valves bottom of towel rad. 1 fixed plumber coming back to do of her one as he only had one with him.
Service valves or radiator valves? If they're the slotted isolation valves you turn off with a screwdriver expect them to leak again if he's replacing like for like.
Oh FFS!
Why is that? I thought they were better than a "normal valve" as they allowed the radiator to be removed without draining?
#30
Afraid not bud, the rad would still need draining if it was being taken off. If there are normal rad valves on then really no need for isolation valves too.
#31
Ah right makes sense I suppose, got to drain rad but not full system, but how to drain rad?? I think i understand.
He is just changing like for like I think.
#32
Ahh just hope that the leak is on the rad side of valve otherwise whole system will need draining or freezing. Sure you'll get there and have fully working central heating just in time for summer
#33
On the 1st one leak was on the system side not the rad side but my pal changed it without to much fuss. He is going to change the other one as it's showing signs of deterioration. Seems ok now with only 1 changed so far.

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